This "Architecture: the lost years" keynote from uncle bob was helpful for me: https://www.youtube.com/watch?v=WpkDN78P884 https://www.youtube.com/watch?v=WpkDN

This "Architecture: the lost years" keynote from uncle bob was helpful for me: https://www.youtube.com/watch?v=WpkDN78P884 https://www.youtube.com/watch?v=WpkDN78P884 I've also struggled with this notion of "untestable" code. Untestable code seems to usually be a big pile of function calls. Testable code seems to be little islands of functionality which are connected by interfaces where only data is exchanged. Practically, this seems to be about shying away from interfaces which look like 'doThis()', 'doThat()', and more like 'apply(data)'. Less imperative micro-management and more functional-core/imperative-shell. Edit: a network analogy might be: think about the differences between a remote procedure call API vs. simply exchanging declarative data (REST).